MEPS 464:167-178 (2012)  -  DOI: https://doi.org/10.3354/meps09869

ABSTRACT: The northern shrimp Pandalus borealis is an important prey species in North Atlantic marine systems and is the target of major fisheries. It reaches its southern limit of distribution in the western Gulf of Maine (GOM), where temperature is thought to play an important role in its stock dynamics. We examined recruitment dynamics of northern shrimp P. borealis in the GOM from 1968 to 2011 and before and after 1999, when a shift to warmer temperatures occurred (Friedland & Hare 2007). Recruitment was related to temperature during all 3 time periods and was related to the reproductive output of the population from 1968 to 2011 and 1968 to 1999 but not in the most recent period (2000 to 2011). Colder temperatures during the pelagic larval stage were associated with higher recruitment. Recruitment variability increased coincident with the 1999 temperature shift; other changes in the physical environment and lower trophic levels of the GOM have been seen as well. Whether the increase in recruitment variability signals a regime shift in the GOM is not yet clear. Increasing the reproductive potential of GOM northern shrimp through conservation measures could help compensate for increasingly unfavorable environmental conditions (warming) and increase the chances of preserving this population and its ecological role in the GOM.

KEY WORDS: Recruitment variability · Stock-recruitment · Temperature effects · Climate change · Ecological indicators · Northern shrimp · Regime shift · Gulf of Maine